slow, yet if the elastick force of this Medium be exceeding
great, it may suffice to impel Bodies from the denser parts of the
Medium towards the rarer, with all that power which we call Gravity. And
that the elastick force of this Medium is exceeding great, may be
gather'd from the swiftness of its Vibrations. Sounds move about 1140
_English_ Feet in a second Minute of Time, and in seven or eight Minutes
of Time they move about one hundred _English_ Miles. Light moves from
the Sun to us in about seven or eight Minutes of Time, which distance is
about 70,000,000 _English_ Miles, supposing the horizontal Parallax of
the Sun to be about 12''. And the Vibrations or Pulses of this Medium,
that they may cause the alternate Fits of easy Transmission and easy
Reflexion, must be swifter than Light, and by consequence above 700,000
times swifter than Sounds. And therefore the elastick force of this
Medium, in proportion to its density, must be above 700000 x 700000
(that is, above 490,000,000,000) times greater than the elastick force
of the Air is in proportion to its density. For the Velocities of the
Pulses of elastick Mediums are in a subduplicate _Ratio_ of the
Elasticities and the Rarities of the Mediums taken together.

As Attraction is stronger in small Magnets than in great ones in
proportion to their Bulk, and Gravity is greater in the Surfaces of
small Planets than in those of great ones in proportion to their bulk,
and small Bodies are agitated much more by electric attraction than
great ones; so the smallness of the Rays of Light may contribute very
much to the power of the Agent by which they are refracted. And so if
any one should suppose that _AEther_ (like our Air) may contain Particles
which endeavour to recede from one another (for I do not know what this
_AEther_ is) and that its Particles are exceedingly smaller than those of
Air, or even than those of Light: The exceeding smallness of its
Particles may contribute to the greatness of the force by which those
Particles may recede from one another, and thereby make that Medium
exceedingly more rare and elastick than Air, and by consequence
exceedingly less able to resist the motions of Projectiles, and
exceedingly more able to press upon gross Bodies, by endeavouring to
expand it self.

_Qu._ 22. May not Planets and Comets, and all gross Bodies, perform
their Motions more freely, and with less resistance in this AEthereal
Medium than in any Fluid, which fill